Association between acute kidney injury and late-onset sepsis in newborns.

BACKGROUND: Acute kidney injury (AKI) is a frequent complication in neonates admitted to the neonatal intensive care unit (NICU), particularly among preterm and low birth weight infants. The aim was to evaluate the incidence, timing, and risk factors of AKI in neonates, with emphasis on its association with late-onset sepsis which remains understudied. METHODS: This retrospective cohort study reviewed 5406 neonatal charts at King Fahad Medical City, Riyadh, over 8 years. A total of 2025 neonates met the inclusion criteria (≥2 serum creatinine measurements after day 3 of life and ≥2 days of intravenous fluids). AKI was defined using modified Kidney Disease: Improving Global Outcomes (KDIGO) criteria, and late-onset sepsis as culture-positive sepsis lasting >72 hours. Chi-square tests and multivariate logistic regression were used, adjusting for confounders. RESULTS: AKI occurred in 19.6% (396/2025) of neonates, with higher rates among those <29 weeks of gestation (37.6%) and <1 kg (30.9%) birth weight. Neonates with AKI had greater exposure to mechanical ventilation, central lines, and late-onset sepsis. Late-onset sepsis in week 2 (adjusted odds ratio [OR] 1.95; 95% confidence interval [CI]: 1.10-3.43) and multi-week late-onset sepsis (adjusted OR 2.95; 95% CI: 1.35-6.41) were significantly associated with AKI. Stratified analyses showed stronger associations between late-onset sepsis and AKI onset in weeks 2-3. Stage 1 AKI was most common (46.2%) and significantly linked to week 2 and multi-week late-onset sepsis, while Stages 2-3 were associated with multi-week late-onset sepsis alone. CONCLUSIONS: Late-onset sepsis significantly increases AKI risk and severity in neonates, particularly during weeks 2-3. Preventing and promptly managing sepsis may reduce AKI burden in this high-risk population.